title: Differential role of the transcription factor NF-kappaB in selection and survival of CD4+ and CD8+ thymocytes.
abstract: Inhibition of the transcription factor nuclear factor (NF)-kappaB activity leads to a reduction in numbers of CD8(+) single-positive (SP) thymocytes, suggesting a selective role for NF-kappaB in these cells. To further explore the role of NF-kappaB in SP thymocytes, we utilized transgenic models that allowed either inhibition or activation of NF-kappaB. We showed that activation of NF-kappaB played an important role in the selection of major histocompatibility complex (MHC) class I-restricted CD8(+) T cells. Surprisingly, NF-kappaB was not activated in positively selected CD4(+) thymocytes, and inhibition of NF-kappaB did not perturb positive or negative selection of CD4(+) cells. However, enforced activation of NF-kappaB via a constitutively active inhibitor of kappaB (IkappaB) kinase transgene led to a nearly complete deletion of CD4 cells by pushing positively selecting CD4(+) cells into negative selection. These studies therefore revealed a surprising difference of NF-kappaB activation in CD4(+) and CD8(+) thymocytes and suggested that NF-kappaB contributes to the establishment of thresholds of signaling that determine positive or negative selection of thymocytes.
authors.affiliation: Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA.
authors.forename: Eijiro
authors.initials: E
authors.lastname: Jimi
authors.forename: Ian
authors.initials: I
authors.lastname: Strickland
authors.forename: Reinhard E
authors.initials: RE
authors.lastname: Voll
authors.forename: Meixiao
authors.initials: M
authors.lastname: Long
authors.forename: Sankar
authors.initials: S
authors.lastname: Ghosh
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000502:physiology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000502:physiology; D002470:Cell Survival; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D051550:I-kappa B Kinase / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D016328:NF-kappa B / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000276:immunology* / Q000378:metabolism; D013950:Thymus Gland / Q000276:immunology / Q000473:pathology; D014158:Transcription, Genetic; D015854:Up-Regulation; D019014:fas Receptor / Q000276:immunology / Q000378:metabolism
chemical_list: D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D016328:NF-kappa B; D019253:Proto-Oncogene Proteins c-bcl-2; D011948:Receptors, Antigen, T-Cell; D019014:fas Receptor; D051550:I-kappa B Kinase; C496562:Ikbkb protein, mouse